The overall goal of this project is to gain an understanding of the early word-learning processes of children with hearing loss, and to delineate factors that influence language development. The implementation of universal newborn hearing screening programs has created an urgent need to characterize foundational stages of language learning in hard-of-hearing (HH) infants and to develop measures that will guide the course of intervention. A primary focus of early intervention programs is to prevent language delays in HH infants. However, recent studies demonstrate that many HH children are slower than normal-hearing (NH) children to develop similar lexicons, even when intervention is provided early. Sources of early delays and individual differences in long-term outcomes in this population are not well understood. Studies of NH and deaf children suggest that early lexical development is influenced by complex interactions of maternal, child, and environmental factors. To date, no studies have systematically examined the factors that influence word learning in HH infants. The first aim of this project is to characterize the rate and course of word learning in HH children in the context of mother-child interaction. Vocabulary growth will be monitored longitudinally at close intervals over an extended period of time in both NH and HH infants and children, with focus on identification of shifts in word learning processes and internal and external factors that influence vocabulary growth. The results of these studies will provide baseline data on word learning in HH children, as well as guidelines for measuring progress and adjusting interventions in clinical settings. The second aim is to test the hypothesis that HH children experience difficulty learning through indirect routes, such as overhearing. Word-learning experiments, parent surveys, and monitoring of pronoun acquisition will be conducted to determine if HH children are able to learn words from incidental exposure. These studies may help guide the selection of amplification to improve the audibility of speech. The final aim is to explore the role of children's social understanding in vocabulary development, and to determine how conversations about thoughts and feelings influence children's knowledge. Three experiments will examine relationships between vocabulary and theory-of-mind skills. The outcomes should provide direction for early interventionists in their efforts to promote nurturing caregiver-child interactions. [unreadable] [unreadable]